/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.actionbarsherlock.internal.view.menu;

import android.content.Context;
import android.os.Parcelable;
import android.view.ViewGroup;

/**
 * A MenuPresenter is responsible for building views for a Menu object. It takes
 * over some responsibility from the old style monolithic MenuBuilder class.
 */
public interface MenuPresenter {
    /**
     * Called by menu implementation to notify another component of open/close
     * events.
     */
    public interface Callback {
        /**
         * Called when a menu is closing.
         * 
         * @param menu
         * @param allMenusAreClosing
         */
        public void onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing);

        /**
         * Called when a submenu opens. Useful for notifying the application of
         * menu state so that it does not attempt to hide the action bar while a
         * submenu is open or similar.
         * 
         * @param subMenu Submenu currently being opened
         * @return true if the Callback will handle presenting the submenu,
         *         false if the presenter should attempt to do so.
         */
        public boolean onOpenSubMenu(MenuBuilder subMenu);
    }

    /**
     * Initialize this presenter for the given context and menu. This method is
     * called by MenuBuilder when a presenter is added. See
     * {@link MenuBuilder#addMenuPresenter(MenuPresenter)}
     * 
     * @param context Context for this presenter; used for view creation and
     *            resource management
     * @param menu Menu to host
     */
    public void initForMenu(Context context, MenuBuilder menu);

    /**
     * Retrieve a MenuView to display the menu specified in
     * {@link #initForMenu(Context, Menu)}.
     * 
     * @param root Intended parent of the MenuView.
     * @return A freshly created MenuView.
     */
    public MenuView getMenuView(ViewGroup root);

    /**
     * Update the menu UI in response to a change. Called by MenuBuilder during
     * the normal course of operation.
     * 
     * @param cleared true if the menu was entirely cleared
     */
    public void updateMenuView(boolean cleared);

    /**
     * Set a callback object that will be notified of menu events related to
     * this specific presentation.
     * 
     * @param cb Callback that will be notified of future events
     */
    public void setCallback(Callback cb);

    /**
     * Called by Menu implementations to indicate that a submenu item has been
     * selected. An active Callback should be notified, and if applicable the
     * presenter should present the submenu.
     * 
     * @param subMenu SubMenu being opened
     * @return true if the the event was handled, false otherwise.
     */
    public boolean onSubMenuSelected(SubMenuBuilder subMenu);

    /**
     * Called by Menu implementations to indicate that a menu or submenu is
     * closing. Presenter implementations should close the representation of the
     * menu indicated as necessary and notify a registered callback.
     * 
     * @param menu Menu or submenu that is closing.
     * @param allMenusAreClosing True if all associated menus are closing.
     */
    public void onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing);

    /**
     * Called by Menu implementations to flag items that will be shown as
     * actions.
     * 
     * @return true if this presenter changed the action status of any items.
     */
    public boolean flagActionItems();

    /**
     * Called when a menu item with a collapsable action view should expand its
     * action view.
     * 
     * @param menu Menu containing the item to be expanded
     * @param item Item to be expanded
     * @return true if this presenter expanded the action view, false otherwise.
     */
    public boolean expandItemActionView(MenuBuilder menu, MenuItemImpl item);

    /**
     * Called when a menu item with a collapsable action view should collapse
     * its action view.
     * 
     * @param menu Menu containing the item to be collapsed
     * @param item Item to be collapsed
     * @return true if this presenter collapsed the action view, false
     *         otherwise.
     */
    public boolean collapseItemActionView(MenuBuilder menu, MenuItemImpl item);

    /**
     * Returns an ID for determining how to save/restore instance state.
     * 
     * @return a valid ID value.
     */
    public int getId();

    /**
     * Returns a Parcelable describing the current state of the presenter. It
     * will be passed to the {@link #onRestoreInstanceState(Parcelable)} method
     * of the presenter sharing the same ID later.
     * 
     * @return The saved instance state
     */
    public Parcelable onSaveInstanceState();

    /**
     * Supplies the previously saved instance state to be restored.
     * 
     * @param state The previously saved instance state
     */
    public void onRestoreInstanceState(Parcelable state);
}
